U.S. Pat. No. 3,925,224 (1975) describes a detergent additive composition containing a water-insoluble surfactant or water-insoluble/water-soluble surfactant mixtures. The detergent additive composition is said to enhance the detergency of conventional detergent products. The specification discloses that the surfactant must be insoluble at the usage temperatures of the wash liquor. In Examples 1-6 soiled fabrics were washed at 55.degree. C. and rinsed in warm tap water.
U.S. Pat. No. 3,983,078 (1976) discloses compositions and methods for dissolving oils and oily soils employing specific mixtures of short chain and long chain alkylene oxide nonionic surface active agents.
Canadian Pat. No. 860,898 (1971) discloses the use of ethoxylated C.sub.8 -C.sub.15 aliphatic alcohols as detergency improvers. These nonionic surfactants are added to a water-soluble mixed anionic and/or nonionic system.
British Patent 1,118,297 (1968) discloses low-foaming, washing and cleansing compositions containing a detergency adduct which is a water-insoluble ethyoxylated alcohol. The examples assert increased soil removal when the detergent compositions were used at 60.degree. C. rather than 40.degree. C.
Volkov, et al., Kolloid. Zh., 34, 607 (1972) describe the effect of alkali metal cations on the phase transitions of nonionic surfactant solutions. Electrolytes were shown to decrease both the lower and the upper solubility temperatures of the nonionic surfactant .alpha.-hydro-.omega.-(tetradecyloxy) poly (oxyethylene).
Volkov, et al., Ibid., 35, 738 (1973) discuss the phase transformation of aqueous solutions of nonionic surfactants with changes in temperature, concentration, and the extent of oxyethylation.
Harusawa, et al., Colloid and Polymer Sci., 252, 613 (1974) discuss the phase equilibria of water, dodecane, and C.sub.12 E.sub.5 systems.
Olteanu, et al., Rev. Chim. (Bucharest) 24,597 (1973) describe measurements of the phase inversion temperatures of hydrocarbon emulsions with nonionic surfactants.
Typical examples of concentrated liquid detergents are disclosed in U.S. Pat. Nos. 2,086,867, Hall 7/1937; 2,551,634, Price 5/1951; 2,770,599, Henkin 11/1956; 2,947,702, Coskie 8/1960; 3,239,468, Herrick 3/1966; 3,554,916, Kerfoot 1/1971, 3,594,323, Taylor 7/1971; 3,663,445, Augustin 5/1972; 3,697,451, Mausner, et al. 10/1972; and 3,709,838, Mausner, et al. 1/1972.
Liquid detergents are also disclosed in: Canadian Pat. No. 615,853, 2/1961; and British Pat. No. 900,000, 6/1962; 842,813, 7/1960; and 759,877, 10/1956.
Other relevant references include Kastra, Defensive Publication of Ser. No. 182,863, filed 9/22/71 No. T903,009; Kastra, Defensive Publication of Ser. No. 182,883, filed 9/22/71 No. T903,010, and "Emulsions and Detergents", a booklet published by Union Carbide, 1961, especially pp. 7-9.
Other heavy-duty liquid detergent compositions are disclosed by Collins in U.S. Pat. No. 3,869,399, issued Mar. 4, 1975, and in U.S. Pat. No. 3,876,563, issued Apr. 8, 1975. The compositions disclosed in these patents are taught to be in gel form, provided no alcohol or electrolyte is present therein. The references cited at column 1 of each of these patents also disclose a variety of heavy-duty (not necessarily liquid) detergent compositions.
Compositions comprising electrolyte, water, and surfactant which seem to have been "salted-out" of solution by means of the electrolyte are disclosed in U.S. Pat. No. 3,235,505, Tuvell, issued Feb. 15, 1966. See also U.S. Pat. Nos. 3,591,508, Huggins, et al., issued July 6, 1971; and 3,060,124, Ginn, issued Oct. 23, 1962.
Pumpable liquid compositions consisting of concentrated ethoxylated nonionic surfactants and water are disclosed in U.S. Pat. No. 3,419,500, Rytter, et al., issued Dec. 31, 1968.
Non-gelling, concentrated liquid detergents are disclosed in U.S. Pat. No. 3,812,041, Inamorato, issued May 21, 1974.
Pasty spot-treating detergent concentrates are disclosed in U.S. Pat. No. 3,619,119, Felletschin, et al., issued Nov. 9, 1971.
Ethoxylated detergent compositions thickened with a polyvinyl acetate maleate thickener are disclosed in U.S. Pat. No. 2,645,415, Pollok, issued July 14, 1963.
Liquid detergent concentrates are disclosed in U.S. Pat. No. 3,776,581, Cheng, issued Dec. 4, 1973.
Detergents comprising anionic and nonionic surfactants are disclosed in U.S. Pat. No. 3,140,261, Noad, issued July 7, 1964.
German Offen. No. 2,403,229, Anmeldetag, Jan. 14, 1974, Smithies, discloses detergent concentrates with indicator systems.
In spite of the substantial body of work in the area of heavy-duty liquid detergents and heavy-duty detergency boosters, the particular advantages and superior performance of compositions of the type disclosed herein do not appear to have been appreciated heretofore.